The winter transfer window is often derided for its lack of value, a seller's market that clubs should avoid, but shrewd signings can have a huge impact on the rest of the season

ANALYSISBy Ewan Roberts

With clubs reluctant to allow their best players to leave in January, the winter window has garnered a reputation for inflated prices and barrel scraping. Good deals are hard to come by – with Harry Redknapp even likening the scramble for those rare opportunities to “gang warfare” – and recent deals for Fernando Torres and Andy Carroll (who, together, have cost £3.7 million per league goal) have come to typify a market which holds little value to buyers.

“The January transfer market has never been the best transfer market and that has been proven over the years with very few big transfers happening,” said former Manchester United boss Sir Alex Ferguson. “All the big transfers happen in the summer.”

Certainly winter spending dwarfs that of the summer, and, since trading windows were introduced in 2003, Premier League spending has, on average, been £321.8m greater in the summer than winter. Yet both the divisions' record signing, Torres, and the most expensive British player, Carroll, moved in January, while the average spend over the last six seasons has increased to £130m (up from £53m between 2003-07) and there is an increasing awareness that big and bold moves in January can have huge rewards.

As such, it is no surprise that the sides ranked fourth and fifth are historically the highest net spenders in January (buying, on average, £16.1m and £11.8m of talent respectively), with clubs keen to build on strong starts to the campaign and eager to strengthen their challenge for a place in the lucrative Champions League.

Manchester City used the window to buy Edin Dzeko in 2010 and, although he took time to settle in English football, scoring just twice, his solitary goal in a 1-0 over Blackburn was the difference between automatic qualification for the Champions League group stage and a potentially perilous play-off. A year earlier, Arsenal had clung onto their place in the top four thanks to the January acquisition of Andrey Arshavin. The Russian scored or assisted 14 goals in 12 league appearances that season, and the Gunners never lost when he played.

Often, inaction in January can be hugely damaging. In 2011-12, Tottenham sat third going into January just six points behind the league leaders with a game in hand. But Vedran Corluka, Sebastien Bassong, Steven Pienaar and Roman Pavlyuchenko were all sold or loaned out, replaced by veterans Louis Saha and Ryan Nelsen. Spurs' points per game dropped by 0.66 and they missed out on a place in the Champions League.

Sides can do too much, too, as Newcastle would attest. Long before the advent of a winter window, the arrival of Faustino Asprilla is often cited as a reason they lost the title in 1996, while last year they signed six players for £18m and struggled in the second half of the season. But, there was tremendous value to be found, particularly in the £1.4m signing of Yoan Gouffran (who has six goals this season), and the Magpies' success this year owes much to the rebuilding they did in January.

For most of the top sides, January is a chance to tweak the squad, bring in young players (Man United's purchase of Wilfried Zaha, for example), and, occasionally, to take a big step towards gaining or securing a place in the top four. At the other end of the table, the winter window can have a far greater impact on sides battling relegation.

In the last two seasons, each of the bottom seven sides at January (with one exception, Wolves) have posted more points and goals per game after they have had the opportunity to recruit new players. That is of course partly to do with having settled and adapted to the league, especially in the case of the promoted sides, as well as the impact of new managers – Mauricio Pochettino's Southampton is an obvious example.

New Crystal Palace boss Tony Pulis, far from approaching the window with trepidation, is relishing the chance to bolster his squad: “If we can move and manipulate things, [that will] give us a push in the second half of the season. We'll try to make one or two changes if we can, someone who can turn the tide.”

Pulis knows the benefits first hand. James Beattie and Matthew Etherington were recruited in January 2009 (and for barely £5m combined), Stoke City's first year in the top flight. Together they scored or created 13 goals, while Stoke's points and goals per game both went up (by 0.38 and 0.21 respectively).

Even just one shrewd signing can have a major influence on the relegation battle. In the 2011-12 season, and despite all their plaudit-winning possession football, Swansea were the joint-second lowest scorers in the league at the halfway mark. After Gylfi Sigurdsson arrived on loan in January, however, they outscored all their relegation rivals. The Icelander's seven goals and five assists contributed to almost half the Swans' goals, and bumped up their goal tally by 44 per cent.

A more low-key signing that same year was Wigan's purchase of Jean Beausejour. The Chilean allowed Roberto Martinez to switch to the much-hailed 3-4-3 formation as the Latics' points per game soared from 0.78 to 1.47.

Such excellent signings can be particularly bad news for rivals who are less active. While Wigan and Swansea were busy, Wolves made just one signing, Eggert Jonsson, who made just two league starts and the club won only once after January. Seventeen of the last 18 relegated teams (excluding QPR and their mammoth outlay) have averaged a net spend of £0.86m, while those sides who have escaped relegation after being in the bottom three at the start of the window have an average net spend of £3.66m.

Signings don't guarantee safety – just ask Rangers – but they can make a difference, especially relative to sides who do not strengthen. Ground can be caught and momentum established, though signings made out of desperation rarely work, while the league leaders' average spend of £1.14m hints at the benefits of stability.

January is routinely seen as a distraction, a mirage in the midst of a gruelling season that serves up only false hope and over-valued players. But that does not have to be the case. There is both value and genuine quality available (the league's current top scorer, Luis Suarez, signed in January for example), and those who buy wisely can vastly improve their chances of achieving their goals, whether Champions League qualification or Premier League survival.